A couple of years ago I purchased a PSA 16" 1:7 Melonite kit.  I have never been able to get the rifle to shoot near decent groups.  Patterns are all over the place.  I've tried different scopes/mounts with no luck.  I shoot reloads but have tried factory ammo with the same poor results.

I'm shooting 55gr bullets which may not be optimal with a 1:7 barrel but should be way better than what I'm getting.

It's been too long since the purchase to probably get help from PSA so I would appreciate any ideas as to where to start.  I'm assuming this is a barrel issue.  Either a defective barrel or possibly a torque issue.

Most would start with removing the barrel and checking the extension and installing the nut again torqued to spec.  You need a vice, upper vice block, proper lube, wrench/torque wrench for the barrel nut in use.

May want to look in the hometown forum for wherever you are located if you don't have the tools.

what type of groups are you getting with other rifles?

Are you shooting with an optic?  If so, check your mount and ring screws and even try a different optic.  Next thing I would do is remove the MD and check the barrel crown.  And then shoot without the MD to see if that makes a difference.  Barrel nut torque should not be an issue unless it is loose, you can pull the handguard and stick a wrench on the barrel nut to see.  Wouldn't be the first time I have witnessed loose fasteners on assembled units.

What is the profile of the barrel? Is it a government profile? If so, decent groups are going to be hard to come by imo.

With that twist rate, I'd start by trying a couple flavors of premium 62 grain or higher ammo, using your irons at 25 yards.  That way you are removing optic & ammo questions out of the equation.  If it still isn't patterning for shit then I'd start looking closer at the gun.  If it is patterning good at 25, then just move it out to verify if it's still good at 100, 200 etc.

Thanks for the replys.  To answer some questions:  groups with my other AR's are anywhere from 1.5" to 3.5" at 100yds depending on the ammo and optic.  As per my OP, I am shooting with an optic, and that was my first suspect as the optic was new when the rifle was built.  I put that optic on my bull barrel AR and got tight groups, ruling out scope/mount problems.

The barrel is government profile, but so is another of my rifles which will shoot 3" groups at 100yds.

I've considered heavier, better quality bullets but I think it might be a waste of good bullets.  I know patterns will definitely improve with those on 1:7 twist, but the pattern is so erratic I don't feel it's going to make that much difference.

I've got a message in to PSA and am interested to see if they have any interest in helping me with the issue.  Don't think I'll lay a wrench on the upper until I see if they want it back.

I have a PSA A2 Govnt Profile 1:7 barrel from about the same time period.

And yes, with 55 gr ammo the groups are big.  62grn stuff did better, and I wasn't willing to spend the $$ on the 70+grn loads to test how accurate it is iwth them.

Bought a 1:9 barrel recently and built it up into an upper, testing it out and so far looking a LOT better.

If you want accuracy from an AR, the trigger and barrel are the critical parts.  After that it is just feeding it decent ammo

Roughly what size groups were you getting with the 1:7 and 55gr ammo?  What brand barrel did you end up with?

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I am going to discount 55 grain bullets and barrel twist.  I have a build with a 20" BA DMR Performance barrel that is 1:7 twist and it will shoot handloaded 55 grain Hornady SP's into a raggedy cluster @ 100 meters. There is something else afoot here.  As I said earlier, I'd pull the muzzle device and check the crown and then shoot it without the MD to eliminate that factor.  A super long leade in the chamber could also lead to poor accuracy.

Was shooting all the various flavors of whatever PSA was blowing out at stupid prices (wish I had more $ then...) or Walmart was selling by the box - mostly all of the Federal/Independence/American Eagle stuff.  Groups were ~3" at 50 yards. Nice solid concrete bench, rest with bag up front, bag in back, big honkin' scope, super crisp 2.5lb trigger.  Fairly sure it isn't the nut behind the trigger 'cause I can kill golf balls at 100-150 yards with my 10/22 rig...  

New barrel is an el-cheapo $70 special from Bear Creek Armory, 1:9 20" fluted.  Saw it while gettign my barrel for a 762x39 build, saw the 1moa guarantee and figured what the heck.  Using the same Federal/American Eagle cheap ammo and some Tula steel case stuff groups went down to about 2" at 100 yards.  Goal is just at/hair below MOA - I want to shoot golf balls at 220 yards (max range I have reliable/guaranteed access to), they are 1 7/8" diameter.

If I were to go buy a barrel right now for accuracy, other than the known big names (lothar, criterion, krieger, etc) I also know Green Mountain is both reasonable in price and they make super accurate 10/22 barrels.  I would assume the accuracy and quality carry over to the other calibers....

1. - Pull barrel from upper receiver.

2. - True the upper receiver front face with lapping tool.

3. - Reinstall barrel properly bedding the trunion in the upper receiver with one of the various compounds proven to work for this.

4. - Properly reinstall barrel nut.



Anymore that is standard procedure for me on any budget upper I purchase as a complete assembled unit.

Then of course use a proper bullet weight of good quality for your barrel twist.  55-gr. is a little light for a 1:7 twist.  60+ gr. copper or similar solid or 70+ gr. for lead core bullet is more in line with that twist rate.

Government profile barrel also SUCKS !!! The most worthless of all profiles (what else would one expect from something from the government?  "We are from the government and we are here to help" = one of the most terrifying phrases in language).

But I understand, with a budget build, the gov. profile is often what you are stuck with.

But unless the barrel really is a dog it should be able to shoot sub-2-MOA.  And in my experience even PSA's most budget barrels are rarely dogs.

Also, for a true test, you need a rigid test mount that completely takes the human element and sighting system completely out of the equation for a true test.

That's what I call great customer service!  I appreciate this and will contact you immediately.

Hopefully PSA can work out the issues with this barrel.  They are a good company so I look forward to their results.

I've got some good info on this thread and I appreciate all the suggestions.  I would like to know more about lapping the front of the upper, and bedding the trunion.  Any links to how to's on this process would be good.  

There are plenty of YouTube videos still up on this process.  Here is one of the better ones I recommend watching on the process:

https://youtu.be/YqTtjhQ_1RY

He states that for him doing this has tightened up his groups by a 1/4-MOA smaller then before doing it.  I on the other hand have seen my group sizes cut in half by doing this.  All depends on how out of true the front receiver face was to start with and how loose the trunion fit was in the receiver to start with.  Using more budget components (that would be me) it seems to make more difference.

As to twist rates - it's not just twist rate - but combination of twist rate and barrel length.  With a shorter barrel you need a little more twist for the same weight bullet.

If you want to shoot 55-gr. lead core jacketed bullets then for a 16" barrel carbine (or a 14.5"-to-15" barrel with pinned and welded permanent muzzle device that brings it out to 16") then a 1:9 twist does quite nicely.  But you wouldn't want to run a 1:12" twist barrel that short.  1:12 twist is for 20"+ full rifle length barrels with 55gr. lead core jacketed bullets.

The length of the bullet outside of the case from tip to tail is what matters for twist.  Longer (heavier) bullets of the same caliber need a higher RPM to stabilize.  Shorter (lighter) bullets of the same caliber need a slightly slightly lower RPM.

Twist rate in a barrel makes the RPM equivalent to the velocity.  If for example a longer barrel gives you 20% more muzzle velocity then if the twist rates in both barrels were the same the RPM would also be 20% higher as well.  So longer barrels that produce higher velocity with the same load sometimes need a slower twist so as to not overspin the bullet.  Shorter barrels may need a faster twist so as to not underspin the bullet.

Best accuracy for each bullet will be helped by being spun up to a specific RPM range that works best for it.  Overspin above that range or underspin under that range and it hurts the accuracy.

Some people call it "putting the bullet to sleep".  The analogy there is rocking a baby in a rocker to get it to sleep and stay sleeping.  Rock too slow and it don't work, rock too fast and it also don't work.  Different babies require different rocking speeds.

With bullets and spin it's similar but at least it's more consistent and predictable with bullets.  Long bullet for caliber = faster.  Shorter bullet for caliber = slower.

1:7 twist is the fastest twist rate commonly available, so unless your shooting a really short pistol barrel it's going to put longer bullets to sleep the best.  Longer length bullet usually equals a heavier bullet.  Although can also be accomplished by using a bullet of the same weight but made from materials that are less dense.  Solid copper bullets for example are usually noticeably longer for the same weight then lead core jacketed bullets.

Have you cleaned the barrel?

I got a PSA mid length about two years ago that shot like crap. Checked the barrel nut and crown and didn't fund anything so decided to clean it with some jb bore paste, flitz, and bore tech.

Shot a lot better after that.

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